Nice Find. It is indeed a CS solid cast I Infantry button. Please do NOT clean any more than you already have as it devalues the button. I like to just blow the dirt off and leave them alone. Where there is one there are others. The camp i'm digging now has produced over 100 CS I buttons 78 have been the cast I the reason they were lost more than the others is their weight. They are a lot heavier than the 2 piece version
Great find, it is commonly referred to as a local, since it was most likely cast locally and as UCV relics mentions, they were heavy and worked through the thread rather quickly.........
Basically the law reads that if its in a state waterway it belongs to the state.
The state owns all abandoned shipwrecks, remains of shipwrecks, all underwater archeological treasures, artifacts, treasure troves, and other cultural articles and materials regardless of association with any shipwreck on its submerged lands.